The present invention relates to liquid ejection apparatuses.
Typically, an electro-optic apparatus such as a liquid crystal display and an organic electroluminescence display (an organic EL display) includes a transparent glass substrate (hereinafter, a substrate) on which an image is displayed. An identification code (for example, a two-dimensional code) is formed on the substrate for the purpose of quality control and production management. The identification code represents encoded product information including the name of the manufacturer and the product number of the substrate. The identification code is provided by structures (defined by, for example, colored thin films or recesses) formed in selected ones of a number of aligned cells (data cells). The identification code thus represents the encoded product information.
As methods for forming such identification codes, a laser sputtering method and a waterjet method have been proposed (see Japanese Laid-Open Patent Publication Nos. 11-77340 and 2003-127537). Specifically, in the laser sputtering method, an identification code is formed through sputtering of a metal foil involving radiation of laser beams onto the metal foil. In the waterjet method, water containing abrasive is ejected onto a substrate and thus marks the identification code on the substrate.
However, in the laser sputtering method, in order to form the identification code in accordance with a desired size, the distance between the metal foil and a substrate must be set to several to several tens of micrometers. Thus, the opposing surfaces of the metal thin film and the substrate must be precisely formed to be flat and spaced from each other by a distance adjusted accurately in the order of micrometers. As a result, the laser sputtering method is applicable only to limited types of substrates, or cannot be used widely for general substrates. Further, in the waterjet method, water, dust, or abrasive is splashed onto the substrate when forming the code, leading to contamination of the substrate.
To solve these problems, an inkjet method has been focused on as an alternative. In the inkjet method, droplets of liquid containing metal particles are ejected through a liquid ejection head. The liquid droplets are then dried and thus the identification code is provided. The inkjet method is thus applicable to a wider range of substrates and prevents contamination of the substrate in formation of the identification code.
More specifically, in the inkjet method, each liquid droplet is first dried on the substrate after having been received by the substrate. Subsequently, functional material contained in the droplet is baked and thus bonded securely with the substrate. That is, the method includes a drying step for fixing the shape of the droplet and a baking step for baking and solidifying the functional material. The drying and baking steps are essential for forming the identification code having an appropriate shape. Therefore, in order to efficiently perform these steps, a liquid ejection apparatus that performs the inkjet method must include a laser radiating portion in the vicinity of a liquid ejection head. The laser radiating portion radiates laser beams so as to dry and bake the liquid droplets.
The inkjet method is performed on a variety of substrates, which may be defined by panels of different sizes. Further, the positions for forming the identification codes may vary from one panel to another. It is thus necessary to provide an apparatus that can be flexibly used for the inkjet method. Further, it is desired that productivity be improved by quickly drying and baking liquid droplets that have been received by a substrate.